With continuous development of display technology, an active array display utilizing thin film transistors has become a most common flat panel display apparatus whose gate driving circuit is realized by means of a shift register. The shift register comprises a plurality of shift register units connected in cascade, and the respective shift register units output signals in sequence to realize progressive driving of the gates.
The existing shift register unit includes three operational states of sampling, output and reset. In two shift register units adjacent to each other, an output signal of a following shift register unit serves as a reset signal of a previous shift register unit to stop the previous shift register unit from outputting. However, if the previous shift register unit fails to receive the reset signal from the following shift register unit, the previous shift register unit will not stop outputting. Therefore, in the prior art, the reset of the previous shift register unit is controlled by the following shift register unit, and if the reset signal from the following shift register unit fails to be fed back or is delayed to be fed back to the previous shift register unit, the previous shift register unit will not be stopped from outputting at a predetermined timing, which may cause the whole array substrate and even the liquid crystal display to be unable to operate properly. Thus, it is essential to solve a problem in which the shift register unit fails to be reset independently.